ABSTRACT
People seem always to have speculated about worlds in addition to that world they have happened to find themselves in at the time. In the sixth century B.C., the Greek Anaximander, the first of the well-known Western natural philosophers, proposed a model of the cosmos cycling over time, with the old universe destroyed and a new universe produced at the end of each cycle and the start of the next. Today, some cosmologists speculate that the present phase of expansion of our universe may be followed by a contraction—the Big Crunch—and infinitely repeated cycles of expansion and contraction. Such worlds may be called temporally-multiple universes, a series of single universes followed one after the other over time. Temporally-multiple universes are but one type of multiple universe that has gained speculative attention. Anaximander’s successor, Anaximenes, discussed the possibility of spatially-multiple universes, worlds existing simultaneously.
